Cumulative and Coseismic (During the 2016 Mw 6.6 Aketao Earthquake) Deformation of the Dextral‐Slip Muji Fault, Northeastern Pamir Orogen

Abstract

AbstractLocated at the northwestern syntaxis of the India‐Asia convergence zone, the Pamir orogen is characterized by complicated and strong active deformation. Constraining the detailed geometry and kinematics of major active structures is important both for understanding modern tectonic processes and for evaluating potential seismic hazards of the region. Our work focuses on the Muji Fault in the northeastern Pamir. Based on cumulative deformation recorded by landforms and coseismic deformation during the 2016 Mw 6.6 Aketao earthquake, we determine the spatial extent, slip motion, fault‐plane geometry, and slip rate of the fault, on the basis of which we clarify its role in the modern tectonics of the Pamir and investigate its seismic behavior and associated seismic hazards. Our study indicates that (i) the Muji Fault, along with the Kongur Extensional System to its south, acts as a boundary fault that accommodates a relative divergence rate of 1.4–2.0°/Ma between the central‐western and eastern Pamir; (ii) geometric discontinuities along the fault exerted an important control on seismic rupture termination and slip gap formation during the Aketao earthquake; and (iii) the cumulative surface‐faulting deformation cannot be formed coseismically by repetitions of the Aketao earthquake, implying significant aseismic (postseismic and/or interseismic) creeping or possibly larger (approximately Mw 7.2), surface‐faulting earthquakes. Our study highlights the usefulness of correlating cumulative and coseismic deformation patterns in active tectonic investigations and regional seismic hazard evaluations.